Speech acts have been discovered in philosophy as acts that can
be done with words or moves in a language game. They still pose
a challenge to semantic theory where, typically, declarative
sentences are analysed as denoting propositions. The two views
of sentences as containers of information, and as moves in
social interaction, can not easily be reconciled.

Grammar and speech act level are not completely
disconnected. Practically all languages distinguish between
three sentence modes, declarative, interrogative, imperative,
which are prototypically tied to the respective speech acts. But
many more aspects of grammar refer to language's function in
social interaction: The use of subjunctive can serve to
distinguish reported speech acts from executed speech
acts. Particles, discourse adverbs and NPIs can serve as speech
act markers. Examples abound, consider German wohl which turns
questions into self-directed questions: Wer bringt Kaffee mit?
"who will bring coffee?" (real question) Wer bringt wohl
Kaffee mit? "who will wohl bring coffee?" (speaker asks
herself) Doch/denn distinguish verb-initial exclamatives from
yes/no questions: Hat er denn einen Hund mitgebracht? "has he
brought along a dog?" Hat er doch einen Hund mitgebracht!
"And what he did was bring a DOG along!" Intensifiers like
English so can be used to emphasize properties ("He is so
tall.") but arguably (Potts) also (preconditions of) speech
acts ("He is so next in line.").

Historical ties Research on grammaticalization proves that
indirect directive speech acts grammaticalize into grammarical
markers of imperative sentence mood. Strikingly, languages
exhibit exactly those grammaticalization paths that would be
predicted by Searle's theory of indirect speech acts. While this
parallel is satisfactory from a theoretical perspective, its
consequences are largely unexplored. Are similar
grammaticalization patterns known for other indirect speech
acts? Other sentence modes? Why is it that grammars limit
themselves to three sentence modes while major speech act
classifications rest on at least five-six major groups, which
subdivide into many more specific kinds of acts?

Analysis of speech acts
Formal theories of speech acts exist (e.g. SDRT,
Asher/Lascarides, but also philosophical approaches ranging from
Stalnaker/Lewis to Searle/Vanderveken), but are usually phrased
as orthogonal to, and disconnected from truth conditional
semantics of the clause. However, there are many words that have
a meaning both in semantics and at speech act level; consider
quantification into speech acts, cookie conditionals ("if
you're hungry, there are cookies on the table") and
more. Can such cross-domain phenomena be captured in a way that
makes the ties between the two levels maximally transparent?
Related to this is the question whether there is any way to
delimit the number of speech acts, and to come up with clear
criteria to identify and distinguish them.

Speech acts and automatic language processing

Finally, applications in language processing are often based on
a scenario of speaker-machine interaction which involves more
than a simple exchange of propositional content. Such
applications often rest on simple, task-driven models of
"doing things with words". Is there anything that
formal semanticists can learn from such theories that have been
tested against real communication? Can semanticists contribute
something to this type of models?